How do you solve $21 + t = 101$ $21 + t = 101$ ?

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Answer 1 · 2015-12-18T15:40:22

More detailed explanation about method.

$t = 80$ $t=80$

Given: $. . 21 + t = 101$ $color(white)(..)color(blue)(21+t=101)$

$Objective$ $color(brown)("Objective")$
To end up with t on its own on one side of the equals sign and everything else on the other.

$Method$ $color(brown)("Method")$

Turn 21 onto 0 so that $0 + t \to t$ $0+t->t$

$Rule$ $color(brown)("Rule")$
What is done to one side of the equation has to be done to the other to maintain the truth of the equals.

$Solution:$ $color(brown)("Solution:")$

Subtract $21$ $color(green)(21)$ from both sides giving:

$(21 + t) - 21 = (101) - 21$ $color(blue)((21+t)color(green)(-21)=(101)color(green)(-21))$

$21 - 21 + t = 80$ $color(blue)(21color(green)(-21) +t= 80$

$0 + t = 80$ $0+t=80$

$t = 80$ $t=80$

How do you solve 21+t=10121 + t = 101?