Solve by the substitution method.

Question

4m + n = 22

m – 3n = 25

Answer 1

4m + n = 22
m - 3n = 25 -----> m = 3n + 25 {added 3n to both sides}

4(3n + 25)  + n = 22 {substituted (3n + 25) in for m into top equation}
12n + 100 + n = 22 {used distributive property}
13n + 100 = 22 {combined like terms}
13n = -78 {subtracted 100 form both sides}
n = -6 {divided both sides by 13}

m = 3n + 25
m = 3(-6) + 25 {substituted -6, in for n, into m = 3n + 25}
m = -18 + 25 {multiplied}
m = 7 {added}

m = 7 and n = -6