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?