Solve the following systems of equations using the substitution method. What is the value of a? 3a-5b=10 a+7b=12 A) a=5 B) a=6 C) a=1 D) a=7

Graph y ≥ -x^2 - 1. click on the graph until the correct graph appears.

The distribution of the amount of money spent by students for textbooks in a semester is approximately normal in shape with a mean of $235 and a standard deviation of $20. according to the standard deviation rule, how much did almost all (99.7%) of the students spend on textbooks in a semester?

Lines a and b are parallel. what is the value of x? -5 -10 -35 -55