A2: Resultant force calculation help please

So there's a balloon with an upward force of 1.3x10⁶N. The initial accelaration when the balloon is released is 27ms^-2. The total mass of the filled ballloon and its load is M.

Calculate the value of M.

I understand that you need to calculate the resultant force which is upward force-weight
so 1.3x10⁶ - mg

The mark scheme says
ma = 1.3x10⁶ - mg
27m = 1.3x10⁶ - mg
Then they give an answer of M = 3.5x10³kg.

I don't understand how they rearranged to get this answer. Thanks

27m = 1.3x10⁶ - mg
27m + mg = 1.3x10⁶
m = 1.3x10⁶ / (27+9.8) = 3.5x10⁴kg. Are you sure it's not 10⁴?

add mg to both sides of the equal sign and see where you get.