-x + 3y − z = -9
x − 2y + 2z = 8
2x − y + z = 7

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.

What is the sum of the geometric series in which a1 = 7, r = 3, and an = 1,701? hint: cap s sub n equals start fraction a sub one left parenthesis one minus r to the power of n end power right parenthesis over one minus r end fraction comma r ≠ 1, where a1 is the first term and r is the common ratio

Andy has $310 in his account. each week, w, he withdraws $30 for his expenses. which expression could be used if he wanted to find out how much money he had left after 8 weeks?