Question

I don't understand. help ?

Answer 1

1.X=Yx1.60 2.X=12x1.15 3.(Mx1.60)+(Fx1.15)

Answer 2

The fact that they want a variable expression means that they don't want a specific answer to the problem.  The want an expression with an unknown (like x or y) that they can plug in a number if they wanted to solve an equation...

1. The cost of y roses.
Well it tells us that the roses cost $1.60 each.  So if we bought 1 we would multiply it by 1.60 to find the cost.  If we bought 50 we would multiply 50 x 1.60.  Since the number of roses can change we call it a variable and we can replace it with x or y (or anything else for that matter).  Since we have a variable, we can put whatever number we want into it to solve the equation.  So to get back to your problem, the cost of y roses would be...

     $1.60y    that just means it will cost 1.60 x number of roses

2.  Cost of 12 carnations.
In this case we know how much the carnations cost and how many we buy so we just multiply...

12 x 1.15 = $13.80

3.  The cost of m roses and f carnations
That's "some number" of roses and "some number" of carnations. Roses are $1.60 so $1.60m and carnations are $1.15 so $1.15f.  We are buying both so add them together...

$1.60m + $1.15f