Since multiplication and division have a higher priority than addition and subtraction, calculate these first working inside the parentheses because these have the highest priority.
5×5=25; 7×23=161.
4+6(25/6/161-45+90), now the division:
25/(6/161)=25(161/6)=4025/6; simplify the contents of the parentheses:
4+6(4025/6+45), distribute the 6:
4+4025+270=4299.