a) Two cement blocks and three bricks weigh 102lb, as do one cement block and ten bricks. What does one brick weigh?

b) A refrigerator repairman charges a fixed amount for a service call in addition to his hourly rate. If a two-hour repair costs $50 and a four-hour repair costs$74, what is the repairman's hourly rate?

2. Originally Posted by pinkmath135
a) Two cement blocks and three bricks weigh 102lb, as do one cement block and ten bricks. What does one brick weigh?
Let $\displaystyle c$ be the weight of a cement block
Let $\displaystyle b$ be the weight of a brick

then we have the system:

$\displaystyle 2c + 3b = 102$ ....................(1)
$\displaystyle c + 10b = 102$ ....................(2)

solve this system for $\displaystyle b$ and you will have your answer. can you continue?

b) A refrigerator repairman charges a fixed amount for a service call in addition to his hourly rate. If a two-hour repair costs $50 and a four-hour repair costs$74, what is the repairman's hourly rate?
Let $\displaystyle m$ be the hourly rate
Let $\displaystyle x$ be the number of hours the repair takes
Let $\displaystyle b$ be the fixed charge.

then the cost of the repair is given by:

$\displaystyle c = mx + b$

since a two hour repair costs $50, we have:$\displaystyle 2m + b = 50$..................(1) since a four-hour repair costs$74, we have:

$\displaystyle 4m + b = 74$ ...................(2)

thus we need to solve the following system

$\displaystyle 2m + b = 50$ ..................(1)
$\displaystyle 4m + b = 74$ ..................(2)

for $\displaystyle m$

can you continue?

3. Originally Posted by Jhevon
Let $\displaystyle c$ be the weight of a cement block
Let $\displaystyle b$ be the weight of a brick

then we have the system:

$\displaystyle 2c + 3b = 102$ ....................(1)
$\displaystyle c + 10b = 102$ ....................(2)

solve this system for $\displaystyle b$ and you will have your answer. can you continue?

Let $\displaystyle m$ be the hourly rate
Let $\displaystyle x$ be the number of hours the repair takes
Let $\displaystyle b$ be the fixed charge.

then the cost of the repair is given by:

$\displaystyle c = mx + b$

since a two hour repair costs $50, we have:$\displaystyle 2m + b = 50$..................(1) since a four-hour repair costs$74, we have:

$\displaystyle 4m + b = 74$ ...................(2)

thus we need to solve the following system

$\displaystyle 2m + b = 50$ ..................(1)
$\displaystyle 4m + b = 74$ ..................(2)

for $\displaystyle m$

can you continue?