FIND X OF TRIANGLES!?!

Which expression is equivalent to (3^2)^-2 a.-81 b.-12 c.1/81 d.1/12

L2.8.2 test (cst): triangles in the figure, pq is parallel to rs. the length of rp is 5 cm; the length of pt is 30 cm; the length of q7 is 60 cm. what is the length of so? o a. 20 cm 0 0 o b. 6 cm o c. 10 cm od. 2 cm 0 previous

How do you figure out which order to do two step equations in? like which thing do you subtract/add/multiply/divide first? i understand that you do the opposite of whatever's shown on the opposite side, but when?