Question

Seven times the first number plus six times the second number equals 31. Three times the first number minus ten times the second number is 29.

Answer 1

1st number = 5.5

2nd number = -1.25

Explanation:

1) 7x + 6y = 31 (multiply entire equation by 3) → 21x + 18y = 93

2) 3x - 10y + 29 (multiply entire equation by 7) → 21x - 70y = 203

3) 21x + 18y = 93

4) -(21x - 70y = 203) now subtract equation (4) from equation (3) to make the x terms drop out

0 + 88y = -110

y = -110/88 = -1.25 now plug this into equation (1) and solve for x

7x + 6(-1.25) = 31

7x = 38.5

x = 38.5/7 = 5.5