Find the value of ' $\mathrm{a}$ ' if the product of $\mathrm{a}$ and $10$ equals $60$.

When you add $-15$ to a number, the result is $25$. Find the number.

Find the value of $\mathrm{v}$ in equation $\frac{\mathrm{v}}{3}+2=4$

Sahil tried to solve an equation but could`t reach to the correct answer. Following were the steps performed by him to solve the expression.

Solve for $\mathrm{n}:3\mathrm{n}+5\left(\mathrm{n}+2\right)=46$

Step1: $3\mathrm{n}+5\mathrm{n}+10=46$

Step2: $8\mathrm{n}+10=46$

Step3: $8\mathrm{n}=56$

Step4: $\mathrm{n}=\frac{56}{8}=7$

Find the incorrect step.