Question

1) a+b=52÷c=10 | ac+bc=? 2)a-b6=31 c=5 | ac-bc=? 3)ab+ac=42 b+c=21 |D=?

Answer 1

1) a + b = 52   iar c = 10

ac + bc = ?

ac + bc = c × (a + b) = 10 × 52 = 520

2) a - b = 31  iar c = 5

ac - bc =  ?

ac - bc = c × (a - b) = 5 × 31 = 155

3)  ab + ac = 42   si    b + c = 21

ab + ac = a ×( b + c) = 42  

                    b  + c = 21          

  ⇒ a × 21 = 42 ⇒  a = 42 : 21  ⇒ a = 2