How to add and subtract positive and negative fractions? ​

When you are adding or subtracting a negative fraction, you usually want to consider the numerator as negative. The method is just the same, except now you may need to add negative or positive numerators.

Example 1:

Find the sum.

95+(−43)

The LCM of 5 and 3 is 15 .

To add the fractions with unlike denominators, rename the fractions with a common denominator.

95=9 × 35 × 3=2715−43=−4 × 53 × 5=−2015

So,

95+(−43)=2715+(−2015)

Since the denominators are the same, add the numerators.

=27+(−20)15=715

Explanation:

the potential energy of the reactants is 200j.

from the energy diagram, the energy of the product formed is 350j; this means that, this reaction is an endothermic reaction, because it absorbs energy from its environment.