You want to isolate x.
First, lets move 8.60 to th other side:
40 + 8.60 = 7.25x => 48.60 = 7.25x
Now, divide left and right by 7.25
48.60/7.25 = 7.25x/7.25 => x ≈ 6.7 (rounded)
Tip: throw the equation in wolfram alpha.
I'm sure you can work out the other one.
Answer:
10
Step-by-step explanation:
He can purchase 10 roses for $6 each, 60 total + $20 fee = $80
Hi,
The answer will be

.
Now how is that, there is a rule for the right angled triangle which says:
cosθ =

so, if we applied this rule on the lower triangle we can say: cos30°=

and therefore the hypotenuse =

=

.
now in the upper triangle we will apply the same rule so,
cos45°=

and the adjacent side in the upper triangle is

and the hypotenuse is x.
so cos45°=

and then we can say
x=

=

.
What is it that you are looking for ?
x or y ?