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)
$0.00995 is the correct answer.
$3.98/400=0.00995
Answer:
-135
Step-by-step explanation:
-5(9 - 6k)
Let k = -3
-5 ( 9 - 6*-3)
-5 ( 9 + 18)
-5 ( 27)
2x^3-42x-40=0
2x^3-42x=40
2x(x^2-21)=40
a. 2x=40=>x=20
b. x^2=21+40=>x^2=61=>x=+-(radical(61)