It's all correct because...
BODMAS
An initialism of "Brackets, Orders (powers, square roots, etc.), Division and Multiplication, Addition and Subtraction," used as a mnemonic in mathematics for remembering the order of operations when calculating an expression.
example 1: 25/2=12.5 (there is ONLY the division operation)
example 2: 10+15/2=17.5 (in this expression the division operation goes first then the result is added to 10)
