Step-by-step explanation:
x = father's age now
y = son's age now
x = 2y + 10
x - 20 = 5(y - 20) = 5y - 100
using the first in the second equation :
2y + 10 - 20 = 5y - 100
-10 = 3y - 100
90 = 3y
y = 30
x = 2y + 10 = 2×30 + 10 = 60 + 10 = 70
the father is now 70 years old, the son now 30 years old.
Answer:
25%
ratio is 3B : 1G (this means, out of 4 sections, 3 are boys and 1 are girls)
this means that 3/4 of class is boys and 1/4 are girls
1/4 equals 25%
