$11 because you add the 2 and then divide by 3 and 18 plus 15 is 33 and 33 divided by 3 is 11
So for me, how I would do it is move the variables and numbers to one side. So we have the equation 3x-3=2/5x+7. So you would subtract 2/5x to the left side and add 3 to the right side. The equation will then turn out to be 3x-2/5x=7+3. Much more easier right? So just simplify both side, and you will get 13/5x=10. In order to isolate x, you have to divide 13/5 in both side, leaving x= 3 11/13 or 50/13. You can always plug the answer back in to double check :)
Consider one pyramid
Side length of base = 1.5cm and its height is 1 cm
Slant height of one of the lateral faces = sqrt(1^2 + 0.75^2) = 1.25 cm
Area of one of the triangular faces = 0.5 * 1.5* 1.25 = 0.9375 cm^2
There are 8 of these so the required surface area = 8 * 0.9375
= 7.5 cm^2 Answer
