1)1/26(fractie)+1/78+1/52=1/(2x13) +1/(2x3x13) + 1/(4x13) = (2x3+2+3) / (4x3x13)=
=11/156
2)1/38+1/44+1/55= 1/(2x19)+ 1/(4x11) + 1/(5x11)=(2x5x11+5x19+4x19) / (4x5x11x19)=
=281/4180
3)1/56+1/53+1/70=1/(8x7) + 1/53 + 1/(2x5x7) = (5x53+8x5x7 +4x53) / (8x5x7x53)=
=757/14840
4)1/18+1/36+1/48=1/(2x9) + 1/(4x9) + 1/(16x3) = (8+4+3) / (16x9) = 15 / (16x9)=
=(3x5) / (16x9) = 5 / (16x3) = 5/48
