Twice the difference of a number and 9 is equal to three times the sum of the number and 4

When you have 25 numbers, and jake picks 3 random numbers and puts them back, what is the chance bob has of picking those 3 numbers when he picks 6 random numbers (without putting them back)? explain.

Julie buys 2kg of apples and 7kg of pears ? 12.70. the pears cost ? 1.30 per kilogram what is the price per kilogram of the apples? show your working out

Let x = a + bi and y = c + di and z = f + gi. which statements are true?