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40 votes
40 votes
We want to solve the following system of equations using the substitution method.

Equation 1- 4p+7q=92/5
Equation 2- 12p+35q=72
Solve for q

User Zovits
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2 Answers

18 votes
18 votes
It’s -5 when you do the math
User Hammar
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12 votes
12 votes

Ok, so you are given the value of P=q+2

The substitution method tells us that we must insert the value we know, into the second equation, 4P+3q= -27

Doing so will give us 4(q+2)+3q= -27

For right now, lets just focus on the first part, 4(q+2)

We can simplify this by distributing(multiplying) the 4 to whats inside the variables.

This will give us 4q+8

now lets add this back to the rest of the equation >>> 4q+8+3q = -27

We can further simplify by adding like terms >>> 7q+8 = -27

subtract the 8 from both sides >>> 7q = -35

now divide both sides by 7 >>> q = -35/7

Therefor q = -5

EDIT*

now that we know q = -5 we can put q into the equation for P !

we know that p=q+2

so lets put q in now >>> p=(-5)+2

and simplify>>> p = -3

I hope this helps:)

User JosephC
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