d=deana's age
b=bernice's age
sum is 48
b+d=48
8 years from now, dena will be 3 times bernice age
d+8=3(b+8)
ok we gots
d+b=48
d+8=3(b+8)
d+b=48
minus b from both sides
d=48-b
subsitute 48-b into the other equation for d
d+8=3(b+8)
48-b+8=3(b+8)
56-b=3b+24
add b to both sides
56=4b+24
minus 24 both sides
32=4b
divide both sides by 4
8=b
bernice is 8 years old
