An increase in supply and an increase in demand for some goods
will cause equilibrium quantity to rise.
This is because when consumer's consumption increases, they
demand more of a good and the firms are ready to supply more which
increases the quantity of output produced and supplied.
When supply and demand move in the same direction, the quantity
of output produced and sold change's but the effect on price cannot
be determined easily.
Hence, When both supply and demand increases, the quantity
increases.