To add or subtract expressions, expand them to make their denominators the same. Least common multiple of $7$ and $5\times 3$ is $105$. Multiply $\frac{2a}{7}$ times $\frac{15}{15}$. Multiply $\frac{\left(a-1\right)a}{5\times 3}$ times $\frac{7}{7}$.
Do the multiplications in $15\times 2a+7\left(a-1\right)a$.
$$\frac{30a+7a^{2}-7a}{105}+\frac{a}{7}$$
Combine like terms in $30a+7a^{2}-7a$.
$$\frac{23a+7a^{2}}{105}+\frac{a}{7}$$
To add or subtract expressions, expand them to make their denominators the same. Least common multiple of $105$ and $7$ is $105$. Multiply $\frac{a}{7}$ times $\frac{15}{15}$.
$$\frac{23a+7a^{2}}{105}+\frac{15a}{105}$$
Since $\frac{23a+7a^{2}}{105}$ and $\frac{15a}{105}$ have the same denominator, add them by adding their numerators.
To add or subtract expressions, expand them to make their denominators the same. Least common multiple of $7$ and $5\times 3$ is $105$. Multiply $\frac{2a}{7}$ times $\frac{15}{15}$. Multiply $\frac{\left(a-1\right)a}{5\times 3}$ times $\frac{7}{7}$.
Do the multiplications in $15\times 2a+7\left(a-1\right)a$.
$$\frac{30a+7a^{2}-7a}{105}+\frac{a}{7}$$
Combine like terms in $30a+7a^{2}-7a$.
$$\frac{23a+7a^{2}}{105}+\frac{a}{7}$$
To add or subtract expressions, expand them to make their denominators the same. Least common multiple of $105$ and $7$ is $105$. Multiply $\frac{a}{7}$ times $\frac{15}{15}$.
$$\frac{23a+7a^{2}}{105}+\frac{15a}{105}$$
Since $\frac{23a+7a^{2}}{105}$ and $\frac{15a}{105}$ have the same denominator, add them by adding their numerators.
