I don’t understand this question please help

Which expression gives the area of the triangle shown below

Solve x+3y=6 and 4x-6y=6 by elimination . show work !

Suppose a laboratory has a 30 g sample of polonium-210. the half-life of polonium-210 is about 138 days how many half-lives of polonium-210 occur in 1104 days? how much polonium is in the sample 1104 days later? 9; 0.06 g 8; 0.12 g 8; 2,070 g