change the 6 ito - 6 by turning to left side then you will have -3 -6 now you can add them (- + -) is + so you can add them the sign of 6 is greater so the answer is -9
15 is the GcF for 45 and 60
To solve for y, you need to subtract b from both sides so only y is on the left side of the equal sign.
y = c - b
They are similar triangles so 20/4=15/x
solve for x
20x=15*4=60
x=3