Karina uses the system of equations below to compare the monthly utility costs in July and December for electricity, x, and natural gas, y. 750x 17y = 141.61 300x 30y = 75.90 Karina solves the system using linear combination and arrives at the equation 116y = 96.28. She then solves this equation for y. Which statement explains Karina’s solution? The cost of natural gas is $0.17 per unit. The cost of natural gas is $0.20 per unit. The cost of natural gas is $0.72 per unit. The cost of natural gas is $0.83 per unit.