Answer:
15 & 7
Step-by-step explanation:
f - s = 8
f = 8 + s
Twice the first number plus three times the second number is 51:
2f + 3s = 51
Substitute:
2(8 + s) + 3s = 51
16 + 2s + 3s = 51
16 + 5s = 51
5s = 51 - 16
5s = 35
s = 7, the second number
Find f:
f = 8 + 7 = 15, the first number
f - s = 8
15 - 7 = 8
8 = 8