Let the first number be #n#

Then the four consecutive numbers are:

#n" ; "(n+1)" ; "(n+2)" ; "(n+3)#

So :#" "n+(n+1)+(n+2)+(n+3) = 26#

#=>4n+6=26#

Subtract 6 from both sides

#=>4n+6-6=26-6#

#4n+0=26-6" "#

#color(brown)("Notice that the above is the source method that gives the shortcut")#

#color(brown)("approach. Which is: for add and subtract, move it to the other side")#

#color(brown)("of the = and change the sign.")#

Divide both sides by 4

#4/4xxn=20/4#

But #4/4=1#

#n=5#

#color(brown)("Notice that the above is the source method that gives the shortcut")#

#color(brown)("approach. Which is: for multiply, move it to the other side")#

#color(brown)("of the = and divide by it. For divide, move it to the other side")#

#color(brown)("of the = and change it to multiply")#

If the first number is 5 then the numbers are:

#color(blue)(5 + 6 +7+ 8 = 26")#