7x = 3y + 45 8. 7. 2x- 1 = 11 4x + 5y = 19 6x - 3v = 15 For questions 9-11, define variables, set up a system, then solve by substitution or elimination. 9. Erin bought 4 jars of jelly and 6 jars of peanut butter for $19.32. Adam bought 3 jars of jelly and 5 jars of peanut butter for $15.67. Find the cost of a jar of peanut butter. 10. Karen makes $5 per hour babysitting and $12 per hour giving music lessons. One weekend, she worked a total of 18 hours and made $139. How many hours did she spend babysitting? 11. Carter has 37 coins, all nickels and dimes in his piggy bank. The value of the coins is $3.10. How many dimes does Carter have