Well, their speeds are (

is Jack's speed, and

is Richard's.

They, together, can paint 12 houses in 35 days. To get a single house, we only have to calculate

which is very close to 3 (a bit below)
Answer:
I believe the answer is 40m2
Step-by-step explanation:
s area of a triangle is
1
2
×
base
×
height
Area of given triangle is
1
2
×
8
×
10
=
80
2
=
40
m
2
.