The first option 12a - 20
If its less than 90, its a right triangle. Hope this helps!
Start off by finding 18% of 13.90.
18%=18/100=0.18
0.18(13.9)=2.5
An 18% tip would be $2.50.
Now, to find out if Lana has enough money, add $2.50 to $13.90 to find out the total amount she would leave. You get $16.40. Since $16.40>$15, the answer is no because the total cost including the 18% tip is greater than $15.
You answer is 3 and here's why...
7x + 5 - 3x - 7 = 10
First you must collect like terms
And that gives us
4x - 2 = 10
Next you must simplify by removing additives
4x - 2 + 2 = 10 + 2
4x = 12
Now you must divide
4x/4 = 12/4
x = 3
Im pretty sure its b im soo sorry if im wrong.