Need help with math

Question

Alexus is ordering a large pizza for lunch. She has $15 dollars in all.  

A large pizza costs $9 and $0.50 per topping. 

Which equation could be used to determine the maximum number 

of toppings t that Alexus can get?

a	$15 = $0.50t
b	$15 = $9 - $0.50t
c	$15 = $9 x $0.50t
d	$15 = $9 + $0.50t

Answer 1

Let t= the number of toppings

each topping is $0.15

so it’s 0.15*t

$15 is her max so let that be your “y”

$9 is the starting price so let that be your “b”

remember the equation y=Mx+b where b is your y-intercept when x=zero

so in this case our “x” is our “t”

so when we set t=0 and we get no toppings our price is 9 dollars

m is our slope or in this case the rate our prize increases per topping

price=price increase per topping t plus 9 dollars for our starting cheese pizza price

y= price to spend

t= toppings

b= 9 dollars

m= 0.15

now put it all together

we want our y to be 15 and our t as our unknown

plug in our calculated slope and intercept

y=0.15t+9

answer D