When should you record a 1in the tens column when you regroup in an addition problem

Will give brainliest what is the value of x? enter your answer in the box.

How does a low unemployment rate affect a nation's economy? a. the nation has a higher number of productive resources. b. the nation can spend more money on for unemployed people. c. the nation can save money by paying lower salaries to a large workforce. reset

Given the two similar triangles, how do i find the missing length? if a=4, b=5, and b'=7.5 find a'