To determine if (-2,10), all we have to do is plug in the appropriate values for x and y into the equation given to us, 5x + 3y = 20. When we use x = -2 and y = 10, we get 5(-2) + 3(10) = 20. When we simplify down, we get -10 + 30 = 20 => 20 = 20. Therefore, the coordinate point (-2, 10) is a solution of 5x + 3y = 20. Hope this helped and have a great day!