Question

a) (2+4+6+...........+100):51


b) (3+6+9+.........+150) :3

Answer 1

a)
(2+4+6+...+100) : 51 =

= 2×(1+2+3+...+50) :51 =

= 2 × 50 × 51 : 2 : 51 =

= 50 × 51 : 51 =

= 50

b)
(3+6+9+...+150) : 3 =

= 3×(1+2+3+...+50) : 3 =

= 50 × 51 : 2 =

= 25 × 51 =

= 1 275

Answer 2

a) (2+4+6+...+100) : 51=
= 2(1+2+3+...+50) :51 
= 2 · 50 · 51 : 2 : 51 
= 50 · 51 : 51 
= 50

b) (3+6+9+...+150) : 3=
= 3·(1+2+3+...+50) : 3 
= 50 · 51 : 2
= 25 : 51
= 1275