X can always be used a 1 .
The answer is 14 because 14×14=196
The exponent of a number says how many times to use the number in a multiplication.
For Example, In 8² , the 2 is the number of times 8 has to be multiplied. In this case It has to multiplied by itself 2 times, 8x8 = 64 so 8² = 64.
Another example is 9³ since the number above is 3 we have to multiply 9 three times, 9x9x9 = 729 which means 9³ = 729.
Hope this helps
The equation for this is a^2+b^2=c^2 so your equation would be 7^2+20^2=X
So you square the 7 and the 20 then take the square root of X and you get
X=21.19
:)