For the first one:
Given:
Cross Multiply:
Simply/expand:
Subtract 4x from both sides:
Factor:
x = 1
Can you rewrite the second question?
It's better that you write \sqrt{z} instead, not sqrt[z]. If you wanted cube root though, you should write sqrt[3]{z}. The nth root is which is \sqrt[n]{x}.
Given:
Multiply by the multiplicative inverse of 6.5 on both sides:
Multiply by on both sides:
Square both sides (principal of powers):