First you need to start by adding positive 4x to both sides since the 4x is a negative. 4x + (-7x) = -3x. Then it is just simply -3x+2 = -7. Since 2 is a positive number subtract both both sides by 2. Then you should get -3x = -9. Then divide both sides by -3 and the answer is x = 3.
At first they bought 40 uniforms for $3,000. When divided, the result came out as 75$ per each uniform. If they only received 40$ back then, 70-40=30. So the difference was 30$ per uniform.