Calculate percentage of a normal distribution using standard deviation

Question

The weight of bags normally distributed with a standard deviation of $5$ $kg$.
Given that $50$% of the bags weigh more than $55$ $kg$, how can we calculate the percentage of bags that weigh less than $65$ $kg$?
My try:
We know that $P(X>55)=50$%, but know we need to calculate $P(X<65)$, but I'm a bit stuck here.

Answer 1

$$ P\left(X<65\right)=P\left(\frac{X-55}{5}<2\right)=P\left(Z<2\right)=\phi \left(2\right)=97.72 $$