The two angles are corresponding angles, so they are congruent (due to the horizontal lines being parallel)
x+15 = 102
x+15-15 = 102-15 .... subtract 15 from both sides
x = 87
No you could have left it as the last but one line or write them separately as
11/18 + √85 / 18 , 11/18 - √85/18
5353 minutes = 89.22 hours
Maybe the figures should be 53 and 20??
Let's let Billy = A
The formula to use for work problems is
Time = (A*B) / (A+B)
53 = ( (A +20)* A) / (A +20 + A) )
53 = ( A^2 + 20A ) / (2A + 20)
A^2 + 20A -106A -1060
A^2 -86A -1060
A = 96.935
Bobby Mows in 116.935 minutes
In the middle:
x-coordinate= {7-(-1)}/2= 4
y-coordinate= (8-2)/2= 3
So centre is (4,3)
