12k-1 is the simplified answer
3x + 5y = 1 . . . . . . . . (1)
7x + 4y = -13 . . . . . . .(2)
(1) x 7: 21x + 35y = 7 . . (3)
(2) x 3: 21x + 12y = -39 .(4)
(3) - (4) = 23y = 46
y = 46/23 = 2
72 × 1.4666666666667 = 105.6 feet per second
Answer:
18
Step-by-step explanation: