Answer:
Explanation:
b and g are the number of boys and girls, respectively.
b:g = 3:4
b = 3x, g = 4x
3x+4x = 70
x = 10
There are 30 boys.
:::::
(380 beats)/(4 minutes) = (380/4 beats)/minute = (95 beats)/minute
15 minutes × (95 beats)/minute = 1425 beats