Hey man, we’ll first of all you just need to substitute the value of a=4 and b=-1 into the equation and you’ll get your answer. Don’t worry I’ll show you an answer.
Well just lookin at it and guessing I would say the estimate would be 777 bc u know that 8+9=17 den carry the one and u know that 1+6=7 and u know that 5+2=7 and yea Hope this help good luck have a nice nite
