Estimate what is 130% of i already know that it is exactly 26. though i need to know how you can go upon estimating it

130% is pretty close to 150%, which means "the whole thing, plus another half."

If we wanted to find 150% of 20, we just take the whole thing (20) and add another half (10), getting a slight overestimation of 20 + 10 = 30. Compare this to the actual answer, 26, and you see that we're only about 4 off.

Edit: The 125% estimate is actually a lot closer than mine, so I'd go with that!