There are 20 miles is Sheng from his home.
After 45 minutes you will have painted 4*45=180 square feet.
so the total number of painted area, y, is:
y=180+x*(3+4) after the 45 minutes
where x is the number of minutes AFTER THE 45 minutes:
if y is 1000 then
1000=180+x*7
820=x*7
x=117.14
so 117 minutes, or one hour and 57 minutes.
First, simplify. Combine like terms
10x - 3x = 7x
7x + 1 = x + 4
Isolate the x. Subtract x from both sides, and 1 from both sides
7x (-x) + 1 (-1) = x (-x) + 4 (-1)
7x - x = 4 - 1
Simplify
6x = 3
Isolate the x. Divide 6 from both sides
6x/6 = 3/6
x = 1/2
1/2, or 0.5 is your answer for x.
hope this helps
