Idon't get this can someone solve/ me with this appreciate it you

Which of the following is the equation that says that the product of a number and ten is equal to 20 percent of that number ? a) 10n= 2.0n b) 10+n=.20n c) n+ .20n=10 d) 10n=0.20n

Ten times the square of a non-zero number is eqaul to ninety times the number

Can someone factor this fully? my friend and i have two different answers and i would like to know if either of them is right. you in advance. a^2 - b^2 + 25 + 10a