Answer:
It would take Angelo 10 minutes to construct 20 playing card houses.
first way to solve it (recommended):
Step one: See how much it takes to build one house
4 / 8 = 0.5
0.5 minutes to build one house
Step two: multiply by amount of houses (20)
0.5 x 20
Step three: get your answer!
It would take Angelo 10 minutes to make 20 houses.
second way to solve it (ratios):
Step one: see the ratio of minutes to houses
minutes : houses
4 : 8
Step two: simplify the ratio
4 : 8
1 : 2 (divide both sides by four)
Step three: multiply
x minutes : 20 houses
1 minutes : 2 houses
multiply both sides by 10
10 minutes : 20 houses
Step four: get your answer!
It would take Angelo 10 minutes to make 20 houses.
I hope my answer helped you!