Answer: 6.25 hours
Explanation:
Step 1: find how much he earned from the odd job
3.75 per hour for 4 hours= 3.75x4= $15
Step 2: Write an inequality
4x+15≥40
Breaking it down:
'4x' means $4 per hour for an unknown number of hours, or just "a number of hours". The reason why you put the x next to the number is because to find the total amount of money he made from that job, you'll have to multiply 4 by however many hours he worked.
15 stands for the amount of money he has right now. He finished the job that paid 3.75 an hour, so don't put an x next to the 15.
40 is the amount of money he needs.
the ≥ sign means "greater than or equal to". In other words, to be able to buy the gift, he needs 40 or more dollars. The line underneath means "greater/less than or equal to". Also, the reason why I didn't put the normal greater sign that looks like >, is beacause that would be saying he needs MORE than 40 dollars to buy the gift, which is not a true statment.
Step 2: Solve the inequality
Solving an inequality is no different from solving an algebra equation. You just ignore the ≥ sign.
4x+15≥40
#1: Always do the inverse operation on the left side number first, never the x term. In other words, always start with addition or subtraction:
See how there is a +15. do the operate equation by subtracting 15 from both sides.
4x+15-15 ≥ 40-15
4x≥25
Now divide both sides by 4. This is because 4x stands for "4 multiplied by x" and the opposite of multiplication is division.
4x/4 ≥ 25/4
x≥6.25
Step 4: Checks
Substitute x for 6.25, but write it as en equation.
4x+15=40
4x6.25 +15 = 40
25+15= 40
40=40
Correct ✅
Answer= He needs to work 6.25, or 6 1/4, or 6 hours and 25 minutes, in order to have enough money for the gift.