91Ó°ÊÓ

A symbol we usually pick letters to be symbols, usually represents a number. Any letter you choose can be a variable.

A variable is a symbol that stands in for an unknown value in a mathematical expression. A variable expression is a combination of terms and mathematical operations that contains at least one variable. Example a + 2x + 10

An equation is a mathematical statement that two expressions are equal. The solution of an equation is the value that when substituted for the variable makes the equation a true statement.

Example: 3x + 5 = 14 is an equation, in which 3x+5 and 14 are two expressions separated by an ‘’equal’’ sign.

The equation given in the question:$−4t=28$

On simplification

$\begin{array}{l}−\text{ â¶Ä‰}4\text{ â¶Ä‰}·\text{ â¶Ä‰}t\text{ â¶Ä‰}=\text{ â¶Ä‰}28\text{ â¶Ä‰}\\ \frac{−\text{ â¶Ä‰}4\text{ â¶Ä‰}·\text{ â¶Ä‰}t}{−\text{ â¶Ä‰}4}\text{ â¶Ä‰}=\text{ â¶Ä‰}\frac{28}{−\text{ â¶Ä‰}4\text{ }}\text{ â¶Ä‰â€‰â¶Ä‰â€‰Divide â¶Ä‰both â¶Ä‰sides â¶Ä‰by â¶Ä‰the â¶Ä‰coefficient â¶Ä‰}(\text{ â¶Ä‰}−\text{ â¶Ä‰}4\text{ â¶Ä‰})\text{ â¶Ä‰of â¶Ä‰}t\text{ }\\ ⇒\text{ â¶Ä‰}t\text{ â¶Ä‰}=\text{ â¶Ä‰}−\text{ â¶Ä‰}7\end{array}$

From the equation $−4t=28$ we get the value of the variable‘t’ is negative 7.