SELECT sum(m.rgcur), sum(t.tax_cur), sum(h.hours)
FROM py_ehmast m
	INNER JOIN (
	   	SELECT ehmast_id, sum(tax_cur) AS tax_cur FROM py_ehtax GROUP BY ehmast_id
	) t
		ON m.ehmast_id = t.ehmast_id
	INNER JOIN (
	   (SELECT ehmast_id, sum(hours) AS hours FROM py_ehhour GROUP BY h.ehmast_id
	) h
		ON m.ehmast_id = h.ehmast_id
GROUP BY ee_id