The initial coordinate of the particle is \((3,7)\)

\(x\)-coordinate is \(3\) unit

\(y\)-coordinate is \(7\) unit

As the body starts from rest so initial velocity \(=0\)

The acceleration of the body along \(x\)-axis \(=4\) units

The acceleration of the body along \(y\)-axis \(=0\)

So, after \(3\) seconds,

Using equation of motion along \(x\)-axis,

\(x=x_0+u t+\frac{1}{2} a t^2\)

as \(u=0 \quad a=4\) units \(\quad t=3\) seconds

\(s=3+\frac{1}{2} \times 4 \times 3^2=2\) lunits

As there is no motion along \(y\)-axis so it will remain unchanged

Hence the final coordinate are \((21,7)\)