Write an equivalent expression by distributing the "_" sign outside the parentheses:
-(5n - 9.1)

Jack did 3/5 of all problems on his weekend homework before sunday. on sunday he solved 1/3 of what was left and the last 4 problems. how many problems were assigned for the weekend?

At store a, erasers are sold individually. the cost y of x erasers is represented by the equation y=0.75x. the costs of erasers at store b are shown in the graph.

Huong is organizing paperback and hardback books for her club's used book sale. the number of paperbacks is 12 less than three times the number of hardbacks. huong had 162 paperbacks. how many hardback books were there?