Correct the answer is -55
2+1=3
15/3=5
split the 3 5's in ratio 2:1 and you get 10:5
Answer:
Speed of plane in still air: 490 mile/hour
speed of wind: 70 mile/hour
Step-by-step explanation:
still speed = x wind speed = w
with wind: speed = still + wind
(x+w) * 3 = 1680 ...a
against wind: speed = still - wind
(x-w) * 4 = 1680 ...b
b-a ... 4x-4w-3x-3w = 0
x-7w = 0
x = 7w
substitution: (7w+w)*3 = 1680 8w = 560 wind speed (w) = 70
still speed (x) = 7w = 490 mile/hour
Answer:
x= 13
Step-by-step explanation:
x + 8 = 21
x + 8-8 = 21-8
x = 13
9^4 + 3^3
= 9•9•9•9 + 3•3•3
= 6,561 + 27
= 6,588