Brian has saved $15 a week for x weeks he spends $50.00. Write an expression that shows how much money he has left

Can someone with this one pre-calc question? the finishing time for a runner completing the 200-meter dash is affected by the tail-wind speed, s. the change, t, in a runner's performance is modeled by the function shown below: t= 0.0119s^2 - 0.308s - 0.0003 predict the change in a runner's finishing time with a wind speed of 3 meters/second. note: a negative answer means the runner finishes with a lower time. round to the nearest hundredth.

How do i do this? i don’t understand

Yahir designs bracelets. he uses between 9 and 15 red and yellow beads in the ratio of 2 red bead to 5 yellow beads. drag the beads into the container to meet these requirements