Answer:
4 boys, 3 girls
Step-by-step explanation:
brothers of John ⇒ x
sisters of John ⇒ y
John has as many brothers as sisters:
- x = y
brothers of Emily ⇒ x + 1 (Emily have the same amount of brother as John, plus one (John))
sisters of Emily ⇒ y -1 (Emily have the same amount of sister as John, minus one (herself))
Emily has twice as many brothers as sisters:
- 2 (y-1) = x+ 1
Now we have a system of 2 equations and 2 variables
x=y (I)
2y - 2 = x + 1 (II)
____________
Replace x in equation II
2y - 2 = y + 1
2y - y = 2 + 1
y = 3
____________
Replace y in equation I
x = y = 3
That mean that John have 3 brothers plus himself, there is 4 boys in the family and John have 3 sister, so there is 3 girls in the family
