When sides are the same then the triangles are congruent.
A1B1 = AB/2, B1C1 = BC/2, C1A1 = CA/2
where A1, B1 and C1 are the midpoints of the sides of Δ ABC.
1 ) A1B1 = C1B, C1B1 = C1B1, B1C1 = A1B
Three sides are equal ( SSS ) so ΔA1B1C1 = ΔBA1C1
2 ) A1C1=AB1, B1C1=B1C1, A1B1=AC1
SSS, ΔA1B1C1 = ΔAB1C1
3 ) B1C1 = CA1, B1A1=B1A1, A1C1= CB1
SSS, ΔA1B1C1 = ΔCA1B1
Therefore: ΔABC = 4 * ΔA1B1C1.
Area of ΔA1B1C1 : Area of the rest of ΔABC = 1 : 3
Picture is in the attachment.