Mariel wrote these checks from her checking account: $10, $10, $31, and $10. which number shows the change in the balance of her checking account?
a: $ -61
b: $ -1
c: $ 1
d: $ 61

Tommy buys a sweater that is on sale for 40% off the original price. the expression p -0.4p can be used to find the sale price of the sweater, where p is the original price of the sweater. if the original price of the sweater is 50, what is the sale price?