Primary 4 Math Question

Hi all,
may I ask whether my answer for the following Math question is correct?

John's monthly salary is twice the amount he saved in April.He saved $3500 in April.He saved $4200 less than the amount he spent in May.
How much is his monthly salary?
How much did he save in May?

$3500x2=$7000
His monthly salary is $7000
$7000-$4200=$2800
$2800/2=$1400
He saved $1400 in May.