using the distributive property we know we distribute by multiplying the outside values to those inside of the parentheses
outside values: 2
inside values: 5 and r
now multiply out inside values by the outside values
2x5 = 10
2xr = 2r
now plug these values back in for the inside values and take away the outside value and the parentheses
so 2(5+r) using the distribution property is 10+2r
