Question

a-b =5 ; a^2-b^2= 70 ; a+b=?

Answer 1

$a - b = 5$

${a}^{2} - {b}^{2} = 70$

$(a - b)(a + b) = 70$

$5(a + b) = 70 \: | \div 5$

$a + b = 14$

Answer 2

a² - b² = (a+b)(a-b) = 70

              (a+b) × 5  =  70
                    
                     a + b = 70:5 = 14 !!!