1. Set up the equation for the volume of the pyramid and make $h$ the subject
Let the height of the pyramid be h.
V=31×base area×h
345+32=31(25+7)h
h=7+253(345+32)
h=7+251025+96
2. Rationalise the denominator by multiplying by the conjugate
h=7+2596+1025×7−257−25
h=72−(25)2(96+1025)(7−25)
3. Expand the numerator and simplify the expression
h=49−2096(7)−96(25)+1025(7)−1025(25)
h=29672−1925+7145−1020
h=29−348+5225
h=−12+185
答案−12+185