Selling price from margin: cost ÷ (1 − margin). Optional 15% VAT is added only if you are VAT-registered.
Then put the price on a quote.
Pricing math
Margin is not markup
If a job costs SAR 700 and you want a 30% margin, the selling price before VAT is SAR 1,000. Adding 30% to cost only gets you SAR 910 and about 23% margin.