Is -1.8x-11.76y+(10.8+3.06)-3.06 equivalent to -1.8x-11.76y +10.8

Find the value of 1715⋅211.though these numbers aren't quite as nice as the ones from the example or the previous part, the procedure is the same, so this is really no more difficult. give the numerator followed by the denominator, separated by a comma.

Evaluate the expression for the given value of the variable 2×(c2-5) for c=4

Tom can paint the fence in 12 hours, but if he works together with a friend they can finish the job in 8 hours. how long would it take for his friend to paint this fence alone?