Thread: Solving applications: Systems of three Equations

I have this word problem that i am having trouble on i am usually good with word problems but my instructor has completely caught me off guard with this one:

The problem is:
The sum of three numbers is 85. The second is 7 more than the first. The third is 2 more than four times the second. Find the numbers.

So far what i have is:

Let x = the first number
let y = the second number
let z = the third number

x+y+z=85
y=2+x
Z=2+4y

This is where i am stuck. I have read the chapter multiple times and have yet to come up with the correct answer. Am i writing the correct equations for the problem given? If so, what step should i take about solving this? Please help thanks in advanced.

Originally Posted by wcruz1

I have this word problem that i am having trouble on i am usually good with word problems but my instructor has completely caught me off guard with this one:

The problem is:
The sum of three numbers is 85. The second is 7 more than the first. The third is 2 more than four times the second. Find the numbers.

So far what i have is:

Let x = the first number
let y = the second number
let z = the third number

x+y+z=85
y=2+x The second number is 7 more than the first!!
Z=2+4y

This is where i am stuck. I have read the chapter multiple times and have yet to come up with the correct answer. Am i writing the correct equations for the problem given? If so, what step should i take about solving this? Please help thanks in advanced.

The sum of three numbers is 85 .
So x+y+z=85.....(I)

The second is 7 more than the first
so, y = x+7....(II)

The third is 2 more than four times the second
s0, z = 2+4y....(III)

substitute (II) and (III) in (I) and find x,y, and z

So, x+y+z=85

or, x+(x+7)+(2+4y)=85

or, x+(x+7)+(2+4(x+7))=85
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okay got it thanks for your help 8,15,62 this just made life like a million times easier