Which number produces a rational number when add to 0.6

While scuba diving, rajeev dove to a depth of 12.6 feet below the surface of the water and then descended another 8.7 feet. what expression can be used to find rajeev's new position? 12.6 – 8.7 –12.6 – 8.7 –12.6 – (–8.7) 12.6 – (–8.7)

Which shows the correct solution of the equation 1/2a+2/3b=50, when b=30?

Write 5(6x+4)-2(5x-2) in the form a(bx+c) where a,b and c integers and a> 1