Question

Aflati a, b si c stiind ca ab + bc = 69 si a/8 = b/12 = c/15.

Answer 1

ab + bc = 69 
a/8 = b/12 = c/15  ⇒b=12a/8=3a/2      c=15a/8
a×3a/2+3a/2×15a/8=69
3a²/2+45a²/16=69
24a²+45a²=1104
69a²=1104
a²=16
a=4
b=3×4/2=6
c=15×4/8=7,5