One-half the cube of m subtracted by 4

Ijust need to see how to do this. so you don’t have to answer all of them just a step by step explanation of one.

Two times a number plus three times another number equals 4. three times the first number plus four times the other number is 7. find the numbers

Four individuals pool money together to start a new business and agree to split the profits equally. n invests $6,000, x invests $2,000, y invests $8,000 and z invests $4,000. if the profits for the first month were $100,000, y receives than if the profits were divided in proportion to how much they invested.