The sum of nine times and number plus 7

Mr. thompson took five of his children to the bowling alley the cost for children 12 and older is 350 the cost of four children under 12 inch to 25 he spent a total of 1625 how many of his children are 12 and order

How many square feet of outdoor carpet will we need for this whole?

What does the pair of equations y = 1, z = 8 represent? in other words, describe the set of points (x, y, z) such that y = 1 and z = 8?