X=-3 which is a positive value? a x b x^2 c x^3 d x+3

The actual width ( w) of a regulation soccer field is 90 meters (m), and the actual length is 120 meters (m). a coach has drawn a scale model of the field on a blackboard. if the longest side of his drawing is 18 cm, how long is the other side of the drawing( w)?

Awater holding tank measures 105 m long, 50 m wide, and 8 m deep. traces of mercury have been found in the tank, with a concen- tration of 60 mg/l. what is the total mass of mercury in the tank? answer in units of kg.

Can someone me with #s 8, 9, and 11. with just one of the three also works. prove using only trig identities.