Answer: Hope this helps :)
Step-by-step explanation:
a) =Let the boys be x
girls = x-10
so
x + x - 10 = 50
or, 2x = 60
so, x = 30
boys = 30
girls = 30-10 = 20
Therefore, 30 boys participated in the activity.
b) = Let the zilong's stamp be x and miya's stamp be y
so
first
x+y = 40
y = 40-x
now
x - 10 = 2y
x-10 = 2(40-x)
x-10 = 80-2x
or, 3x = 90
so, x = 30
then y = 40-x
y = 40-30 = 10
Therefore, Zilong had 30 stamps and Miya had 10 stamps before.
